Generating an Opening Book for Amazons

Creating an opening book for the game of Amazons is difficult for many reasons. It is a relatively new game so there is little accumulated knowledge and few expert games to draw on. Also, the huge branching factor, over 1000 available legal moves during most of the opening, makes selecting good moves difficult. Still, one or two bad moves in the opening can doom a player to passive play and an almost certain loss, so it is essential for a good program to play the opening well. We discuss a number of possible methods for creating opening books, focusing mainly on automatic construction, and explain which seem best suited for games with large branching factors such as Amazons.